Hi Carpenter,
I was in a similar situation in which I wanted to do a post-grad diploma (which was directly related to my work), and hoped that my company would contribute to the costs.
The way I went about it, was to be really business-like.
I wrote up a business case, showing the advantages to my employer if I did the course, and since it was such a hands-on course, how these advantages could be applied immediately to the company. I then requested a meeting with the company director to pitch the idea to him, and gave him a presentation.
Luckily they agreed to pay 90% of the cost upfront, which I had to pay back if I failed!
Also if the course you want to do is on fri and sat - is that fri after work or during the day? You'd need to be clear on whether it shall impinge on your normal day to day work, and if you are requesting allowances in that area too.
If I were you, I'd try to look at it from every angle, so that you'll have a thought-out answer to whatever questions your employer may have for you.